JP2013201517A - Control method of optical transmission system, optical transmitter, controller and optical transmission system - Google Patents

Abstract

A transmission path characteristic of an optical transmission path can be accurately estimated.
Based on the result of transmitting a known symbol sequence in an optical transmission path including a plurality of optical transmission devices, passing through at least one optical transmission device from one optical transmission device to another optical transmission device. In an optical transmission system that estimates transmission path characteristics of an optical transmission path, control is performed to expand a pass band for a known symbol sequence in at least one optical transmission apparatus through which the optical transmission path passes, and the known symbol series in the optical transmission path And the transmission path characteristics of the optical transmission path are estimated based on the transmission result.
[Selection] Figure 7

Description

  The present invention relates to an optical transmission system control method, an optical transmission device, a control device, and an optical transmission system.

2. Description of the Related Art In recent years, with an increase in transmission data quality, there has been a demand for higher signal bit rates in optical transmission systems using wavelength division multiplexing (WDM) technology. In addition, with the increase in data capacity, the signal frequency is increasing.
On the other hand, in order to improve frequency utilization efficiency, a large-capacity transmission is realized by narrowing the bandwidth of each wavelength-multiplexed signal light and narrowing the bandwidth per channel.

In the optical transmission system as described above, for example, when high-speed transmission such as 40 Gbps or 100 Gbps is realized, the influence of transmission quality deterioration factors such as polarization mode dispersion and wavelength dispersion caused by the transmission path characteristics of the optical transmission path. Cannot be ignored.
Therefore, as an example of a method for suppressing the influence of the transmission quality deterioration factor, for example, research on a digital coherent signal processing technique for digitally processing signal light has been advanced.

To realize an optical transmission device using digital coherent signal processing technology, a technology for estimating signal degradation that occurs while signal light travels through an optical transmission line, a technology for identifying and compensating for the cause of signal degradation from the estimation results, a code Realization of technology to correct errors is required.
Among these techniques, as a technique for estimating signal degradation that occurs while signal light travels through an optical transmission line, for example, a known symbol sequence (hereinafter sometimes referred to as a training signal) is transmitted via the optical transmission line, and transmitted and received. There is a method for estimating signal degradation by comparing results.

Specifically, for example, when a signal light is transmitted (transmitted), before transmission / reception of signal light, a training signal is transmitted through the optical transmission path, and the transmission path of the optical transmission path is based on comparison of the transmission / reception results. Estimate the characteristics. Based on the estimation result, initial parameters for performing digital signal processing in the optical transmission apparatus are set.
In the following Patent Document 1, a fixed data string composed of 01 alternating data and 0-series and 1-series alternating data in which 0 continuation and 1 continuation alternate is transmitted to the optical transmission line, and the number of errors occurring in the 01 alternating data in the receiving device A method is described in which the dispersion compensation amount increase / decrease direction is determined based on the number of error occurrences in the 0-series 1-series alternating data, and the dispersion compensation amount of the variable dispersion compensator is variably controlled.

International Publication No. 2006/137138

As described above, with regard to signal light, by reducing the bandwidth per channel, frequency utilization efficiency is improved and large-capacity transmission is realized.
At this time, the bandwidth of the training signal used for estimating the transmission path characteristics of the optical transmission path may be wider than the bandwidth of the signal light.
In such a case, the training signal may be lost depending on the pass band of the optical transmission device through which the training signal passes.

If the training signal is lost, the transmission path characteristics of the optical transmission path cannot be estimated appropriately, and initial parameter settings for digital signal processing may not be set appropriately.
In such a case, the signal light may be deteriorated or the signal light may not be transmitted accurately.

Accordingly, an object of the present invention is to make it possible to accurately estimate the transmission path characteristics of an optical transmission path.
In addition, the present invention is not limited to the above-described object, and other effects of the present invention can be achieved by the functions and effects derived from the respective configurations shown in the embodiments for carrying out the invention which will be described later. It can be positioned as one of

  (1) As a first proposal, for example, a plurality of optical transmission devices, a known symbol sequence in an optical transmission path from one optical transmission device through at least one optical transmission device to another optical transmission device A method of controlling an optical transmission system that estimates transmission path characteristics of the optical transmission path based on a result of transmitting the optical transmission path, wherein the at least one optical transmission apparatus that the optical transmission path passes through the known symbol sequence Using a control method for an optical transmission system that performs control to expand a band, transmits the known symbol sequence in the optical transmission line, and estimates a transmission line characteristic of the optical transmission line based on a result of the transmission. Can do.

  (2) Further, as a second plan, for example, a plurality of optical transmission devices are provided, which are known in an optical transmission path from one optical transmission device through at least one optical transmission device to another optical transmission device. An optical transmission apparatus through which the optical transmission line of the optical transmission system estimates a transmission line characteristic of the optical transmission line based on a result of transmitting a symbol series, and before transmitting the known symbol series, A control unit that performs control to expand a pass band for a known symbol sequence, and a transmission processing unit that transmits the known symbol sequence through the optical transmission path after the control unit performs control to expand the pass band; Thus, an optical transmission device can be used.

  (3) Further, as a third proposal, for example, a plurality of optical transmission apparatuses and known symbols in an optical transmission path from one optical transmission apparatus through at least one optical transmission apparatus to another optical transmission apparatus A control device for estimating a transmission line characteristic of the optical transmission line based on a result of transmitting the sequence, the control device of the optical transmission system, wherein the optical transmission before transmitting the known symbol sequence A control unit that performs control to expand a pass band for the known symbol sequence in the at least one optical transmission device through which a path passes, and the control unit performs control to expand the pass band, and then the optical transmission path And a processing unit that estimates a transmission path characteristic of the optical transmission path based on a transmission result of the known symbol sequence transmitted in step (1).

  (4) Further, as a fourth plan, for example, a plurality of optical transmission devices are provided, which are known in an optical transmission path from one optical transmission device through at least one optical transmission device to another optical transmission device. An optical transmission system that estimates transmission path characteristics of the optical transmission path based on a result of transmitting a symbol sequence, wherein the at least one optical transmission apparatus is the optical transmission apparatus according to (2) above. A transmission system can be used.

  (5) Further, as a fifth plan, for example, a plurality of optical transmission devices are provided, which are known in an optical transmission path from one optical transmission device through at least one optical transmission device to another optical transmission device. An optical transmission system that estimates transmission path characteristics of the optical transmission path based on a result of transmitting a symbol sequence, and includes the control device described in (3) above can be used.

  It is possible to accurately estimate the transmission path characteristics of the optical transmission path.

It is a figure which shows an example of a structure of an optical transmission system. It is a figure which shows an example of a structure of the optical node shown in FIG. It is a figure which shows an example of a structure of the wavelength selective switch shown in FIG. (A)-(C) is a figure showing an example of change of the pass band of a wavelength selective switch. It is a figure which shows the other structural example of a wavelength selective switch. It is a figure which shows the other structural example of a wavelength selective switch. It is a figure which shows an example of the control method which concerns on 1st Embodiment. It is a figure which shows an example of the control method which concerns on a 1st modification. It is a figure which shows an example of the control method which concerns on a 1st modification. It is a figure which shows an example of the pass-band characteristic of a pass-band variable type wavelength selective switch. It is a figure which shows an example of the pass-band characteristic of a LCOS type wavelength selective switch. It is a figure which shows an example of each port arrangement | positioning of a wavelength selection switch. It is a figure which shows an example of the input / output setting of a wavelength selection switch. It is a figure which shows the other structural example of an optical transmission system. It is a figure which shows an example of the pass-band characteristic for every channel in each optical node of the optical transmission system shown in FIG. (A) is a figure which shows an example of a structure of an optical transmission system, (B)-(D) is a figure which shows an example of the control method which concerns on a 1st modification. It is a figure which shows an example of a structure of the optical transmission system which concerns on a 2nd modification. It is a figure which shows an example of a structure of a network management apparatus. It is a figure which shows an example of the control method which concerns on a 2nd modification. It is a figure which shows an example of the control method which concerns on a 2nd modification.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below is merely an example, and there is no intention of excluding various modifications and technical applications that are not clearly shown in the embodiment and each modification described below. That is, the following embodiments and modifications may be variously modified without departing from the spirit of the present invention.
[1] One Embodiment (1.1) Example of Configuration of Optical Transmission System FIG. 1 is a diagram illustrating an example of the configuration of an optical transmission system according to an embodiment.

  The optical transmission system 1 illustrated in FIG. 1 exemplarily includes an optical node 4-1 having an optical transmitter (Tx) 2 and optical nodes 4-2 to relay signal light from the optical node 4-1. 4- (n-1) (n is an integer of 2 or more) and an optical node 4-n having an optical receiver (Rx) 3 are provided. For convenience of explanation, in FIG. 1, Tx2 in the optical node 4-1 and Rx3 in the optical node 4-n are written to the outside. In the following description, when the optical nodes 4-1 to 4-n are not distinguished, they are simply expressed as the optical node 4.

  In the example shown in FIG. 1, the signal light transmitted from Tx2 is inserted (added) into the wavelength multiplexed signal light transmitted through the optical transmission line by the optical node 4-1, and the optical nodes 4-2 to 4- (n− 1) is passed (through), branched (dropped) by the optical node 4-n, and received by Rx3. The network configuration of the optical transmission system 1 illustrated in FIG. 1 is merely an example, and the optical transmission system 1 includes various networks such as a ring type, a mesh type, a star type, a full connection type, a bus type, and a tree type. You may have a form. The optical transmission system 1 may have a combination of network forms.

By the way, each optical node 4 that functions as an example of an optical transmission device has, for example, a wavelength selective switch (WSS) in order to pass, insert, and branch signal light in wavelength units.
(1.2) Example of Configuration of Optical Node 4 An example of the configuration of the optical node 4 is shown in FIG.

  The optical node 4 shown in FIG. 2 exemplarily includes an optical coupler 41-1, an optical amplifier 42-1, an optical coupler 41-2, an optical receiver (Rx) 3-1, and a WSS 43-1. , An optical transmitter (Tx) 2-1, an optical amplifier 42-2, and an optical coupler 41-3. 2 exemplarily includes an optical coupler 41-4, an optical amplifier 42-3, an optical coupler 41-5, an optical receiver (Rx) 3-2, and a WSS 43-2. And an optical transmitter (Tx) 2-2, an optical amplifier 42-4, and an optical coupler 41-6. Furthermore, the optical node 4 illustrated in FIG. 2 exemplarily includes an optical supervisory channel (OSC) processing device 44-1 having a supervisory control unit 45-1, and an OSC process having a supervisory control unit 45-2. A device 44-2 and a passband control unit 46 are provided. In the following, when WSS 43-1 and 43-2 are not distinguished, they are simply expressed as WSS 43. For convenience of explanation, the direction from the left side to the right side in FIG. 2 is sometimes referred to as up (UL: UpLink), and the direction from the right side to the left side in FIG. 2 is referred to as down (DL). .

With regard to the optical node 4 illustrated in FIG. 2, focusing attention on the uplink, the wavelength multiplexed signal light input to the optical node 4 from the optical transmission line such as an optical fiber is optically amplified by the optical coupler 41-1. The power is branched into a route to and a route to the OSC processor 44-1.
The wavelength-division multiplexed signal light branched in the direction to the optical amplifier 42-1 is amplified by the optical amplifier 42-1, and further power-branched by the optical coupler 41-2 to select the signal light having a desired wavelength. Branching (dropping) and receiving processing is performed by Rx 3-1. Rx3-1 has a digital circuit (DSP: Digital Signal Processor) capable of digitally processing signal light.

  The wavelength multiplexed signal light input from the optical coupler 41-2 to the WSS 43-1 is demultiplexed for each wavelength (channel) by the WSS 43-1, and further, the signal light is inserted (added) for each channel or is left as it is. Whether to pass (through) is selected, and wavelength-multiplexed again and output to the optical amplifier 42-2. The added signal light is supplied to the WSS 43-1 by Tx2-1. Tx2-1 has a digital circuit capable of digitally processing signal light.

The wavelength multiplexed signal light output from the WSS 43-1 is amplified by the optical amplifier 42-2 and then combined with the OSC light output from the OSC processing device 44-2 by the optical coupler 41-3, Output to the transmission line.
On the other hand, paying attention to the downstream, the wavelength multiplexed signal light input to the optical node 4 from the optical transmission line such as an optical fiber is routed to the optical amplifier 42-3 by the optical coupler 41-4 and the OSC processing device 44-. Power diverts to the route to 2.

The wavelength-division multiplexed signal light branched in the direction to the optical amplifier 42-3 is amplified by the optical amplifier 42-3 and then further branched by the optical coupler 41-5 to select the signal light having a desired wavelength. Branching (dropping) and receiving processing is performed by Rx3-2. Rx3-2 has a digital circuit capable of digitally processing signal light.
The wavelength multiplexed signal light input to the WSS 43-2 from the optical coupler 41-5 is demultiplexed for each wavelength (channel) by the WSS 43-2, and further, the signal light is inserted (added) for each channel or is left as it is. Whether to pass (through) is selected, and wavelength-multiplexed again and output to the optical amplifier 42-4. The added signal light is supplied to the WSS 43-2 by Tx2-2. Tx2-2 has a digital circuit capable of digitally processing signal light.

The wavelength multiplexed signal light output from the WSS 43-2 is amplified by the optical amplifier 42-4, and then multiplexed by the optical coupler 41-6 with the OSC light output from the OSC processing device 44-1. Output to the transmission line.
The OSC processing device 44-1 extracts the OSC light included in the wavelength multiplexed signal light that is branched by the optical coupler 41-1, and notifies the control information superimposed on the OSC light to the passband control unit 46, The control information notified from the passband controller 46 is superimposed on the OSC light and output to the optical coupler 41-6. Therefore, the OSC processing device 44-1 includes a monitoring control unit 45-1 that extracts control information superimposed on the OSC light and performs transmission / reception control of the control information.

  Similarly, the OSC processing device 44-2 extracts the OSC light included in the wavelength-division multiplexed signal light split by the optical coupler 41-4, and notifies the passband control unit 46 of the control information superimposed on the OSC light. Or the control information notified from the passband controller 46 is superimposed on the OSC light and output to the optical coupler 41-3. Therefore, the OSC processing device 44-2 includes a monitoring control unit 45-2 that extracts control information superimposed on the OSC light and performs transmission / reception control of the control information.

  The control information includes, for example, an alarm signal indicating that a failure has occurred in the optical node 4, a control signal for controlling the amplification gain in the optical amplifiers 42-1 to 42-4, and attenuation in the WSS 43. A control signal or the like for controlling the amount may be included. The monitoring control units 45-1 and 45-2 notify the occurrence of a failure to a network management apparatus (NMS: Network Management System) based on the control information, or amplify by the optical amplifiers 42-1 to 42-4. The gain may be controlled, or the attenuation amount in the WSS 43 may be controlled.

Here, an example of the configuration of the WSS 43 is shown in FIG.
As shown in FIG. 3, the WSS 43 exemplarily includes an optical coupler 431, passband variable filters 432-1 to 432-5, 2 × 1 optical switches 433-1 to 433-5, and an optical coupler 434. With. The number of passband variable filters 432-1 to 432-5 and 2 × 1 optical switches 433-1 to 433-5 is not limited to the example shown in FIG. 3, and the wavelength multiplexed signal light input to WSS 43 is not limited to the example shown in FIG. It can be appropriately changed according to the number of wavelength multiplexing.

For example, when wavelength multiplexed signal light in which five wavelength signal lights of ch1 (λ1) to ch5 (λ5) (λ1 <λ2 <λ3 <λ4 <λ5) are wavelength-multiplexed is input to the WSS 43 illustrated in FIG. The wavelength multiplexed signal light is split in power by the optical coupler 431 and then input to the passband variable filters 432-1 to 432-5.
The passband variable filter 432-1 passes the signal light of λ1, while blocking the signal light of λ2 to λ5. The pass band variable filter 432-1 is realized by, for example, a low pass filter or a band pass filter. Further, the passband variable filter 432-2 passes the signal light of λ2, while blocking the signal light of λ1 and λ3 to λ5. The passband variable filter 432-2 is realized by, for example, a bandpass filter. Further, the passband variable filter 432-3 passes the signal light of λ3 while blocking the signal light of λ1, λ2, λ4, and λ5. The passband variable filter 432-3 is realized by, for example, a bandpass filter. The passband variable filter 432-4 passes the signal light of λ4, while blocking the signal light of λ1 to λ3 and λ5. The passband variable filter 432-4 is realized by, for example, a bandpass filter. Further, the passband variable filter 432-5 allows the signal light of λ5 to pass while blocking the signal lights of λ1 to λ4. The pass band variable filter 432-5 is realized by, for example, a high-pass filter or a band-pass filter.

  The 2 × 1 optical switch 433-1 selects one of the λ1 signal light output from the passband variable filter 432-1 and the λ1 signal light inserted (added) from Tx, and selects the light. Output to the coupler 434. The 2 × 1 optical switch 433-2 selects either the λ2 signal light output from the passband variable filter 432-2 or the λ2 signal light inserted (added) from Tx. Output to the optical coupler 434. Further, the 2 × 1 optical switch 433-3 selects either the λ3 signal light output from the passband variable filter 432-3 or the λ3 signal light inserted (added) from Tx. Output to the optical coupler 434. The 2 × 1 optical switch 433-4 selects either the λ4 signal light output from the passband variable filter 432-4 or the λ4 signal light inserted (added) from Tx. Output to the optical coupler 434. Further, the 2 × 1 optical switch 433-5 selects either the λ5 signal light output from the passband variable filter 432-5 or the λ5 signal light inserted (added) from Tx. Output to the optical coupler 434.

The optical coupler 434 combines and outputs the signal light of λ1 to λ5 output from the 2 × 1 optical switches 433-1 to 433-5.
Here, the WSS 43 can control the pass band for the signal light of each wavelength (channel), for example, by changing the pass band of each of the pass band variable filters 432-1 to 432-5.

  For example, as illustrated in FIG. 4A, when a certain pass band a is set for the signal light of λ1, the pass band a is changed to the pass band b as illustrated in FIG. 4B. The pass band a or b can be reduced to the pass band c as illustrated in FIG. Such control of the passband is not limited to the WSS 43 having the configuration illustrated in FIG. 3, but a wavelength selective switch 43 using a MEMS (Micro Electro Mechanical Systems) mirror array as illustrated in FIG. The wavelength selective switch 43 using LCOS (Liquid Crystal On Silicon) as exemplified in FIG.

By the way, when the signal light is digitally processed in the optical transmitters (Tx) 2-1 and 2-2 and the optical receivers (Rx) 3-1 and 3-2 in the optical node 4, the transmission path of the optical transmission path A parameter for digital signal processing may be set based on an estimation result of characteristics.
For example, before signal transmission / reception, such as when a signal is added (started up), a known symbol sequence (training signal) is transmitted through a channel that transmits / receives signal light via the optical transmission path, and the transmission is performed. Based on the result, the transmission line characteristic of the optical transmission line is estimated, and based on the estimation result, initial parameters for digital signal processing are set. Hereinafter, a series of processes related to the initial parameter setting is also simply referred to as an initial process.

  However, when the bandwidth of the signal light is smaller than the bandwidth of the training signal, the pass band of the WSS 43 may be set according to the bandwidth of the signal light. In such a case, since the pass band in the WSS 43 is narrower than the bandwidth of the training signal, the training signal may be lost. As a result, the transmission line characteristics of the optical transmission line cannot be estimated properly, the initial parameters for digital signal processing cannot be set appropriately, the signal light is deteriorated, and the signal light can be transmitted accurately. There may be no.

Therefore, the passband control unit 46 of this example performs control to expand the passband of the WSS 43 before transmission of the training signal.
Specifically, for example, the passband control unit 46 detects the channel that is the target of the initial process based on the control information notified from the OSC processing devices 441 and 44-2, and the passband of the channel in the WSS43. Control to enlarge.

In other words, the passband control unit 46 functions as an example of a control unit that performs control to expand the passband for the training signal before transmitting the training signal.
The wavelength selective switches 43-1 and 43-2 function as an example of a transmission processing unit that transmits a training signal through an optical transmission line after performing control to expand the passband.
Thereby, it is possible to reduce the loss received by the training signal for estimating the transmission line characteristic of the optical transmission line, and to accurately estimate the transmission line characteristic of the optical transmission line. As a result, initial parameter settings for digital signal processing can be appropriately set, and signal light can be reliably transmitted and received.

(1.3) Example of Control Method Here, an example of a method for controlling the passband of the WSS 43 will be described with reference to FIG.
As illustrated in FIG. 7, first, when the control is started with the start of a signal or the like (step S10), the passband control unit 46 is notified from the OSC processing devices 44-1 and 44-2. On the basis of the control information, the channel that is the target of the initial process is detected (step S11). That is, the passband control unit 46 detects a channel for transmitting a training signal based on the control information notified from the OSC processing devices 44-1 and 44-2.

  Then, the passband control unit 46 expands the passband of the WSS 43 for the channel detected in step S11 (step S12). Note that the extent to which the pass band of the WSS 43 is expanded can be determined based on the bandwidth of the training signal to be transmitted. Specifically, for example, the pass band of the WSS 43 may be expanded so that the loss that the training signal undergoes when passing is less than or equal to a predetermined threshold.

  Further, for example, the processing in step S12 may be realized by expanding the passband of the channel detected in step S11 to the passband of the adjacent channel adjacent to the channel. Note that the pass band width of the training signal may be expanded by performing control to expand the pass band to at least one of the adjacent channels. Further, the processing in step S12 may be performed in the WSSs 43 of all the optical nodes 4, or in the optical node 4 in which at least one of the adjacent channels adjacent to the channel detected in step S11 is unused. While the process is performed, the process of step S12 may not be performed in the other optical nodes 4. In this way, the influence on other channels on the network path can be suppressed by the passband expansion control.

  Next, the passband control unit 46 transmits a training signal in the channel whose passband is expanded (step S13). For example, the passband control unit 46 can start transmission of the training signal by notifying the Tx in the optical node 4 that the processing in step S12 has been completed. In addition, as a training signal, you may use the alternating signal which 0 value and 1 value generate | occur | produce alternately, for example.

The Rxs 3-1 and 3-2 in the optical node 4 that is the receiving destination of the training signal estimate the transmission path characteristic of the optical transmission path based on the transmission result of the training signal. At this time, since the optical node 4 can use the sideband of the training signal for the estimation process of the transmission path characteristic, it can accurately estimate the transmission path characteristic.
Then, the passband controller 46 determines whether or not the estimation of the transmission line characteristics of the optical transmission line by the Rx 3-1 and 3-2 in the optical node 4 that is the receiving destination of the training signal is completed (Step S <b> 14). ), When it is determined that the estimation of the transmission path characteristics of the optical transmission path is not completed (No route in step S14), the passband control unit 46 waits until the estimation of the transmission path characteristics of the optical transmission path is completed. . Note that the determination process in step S14 can be performed, for example, by receiving a report of completion of the process from the apparatus that has performed the transmission path characteristic estimation process of the optical transmission path.

On the other hand, when it is determined that the estimation of the transmission path characteristics of the optical transmission path is completed (Yes route in step S14), the passband control unit 46 restores the passband expanded in the WSS 43 (step S15).
Then, the passband control unit 46 performs parameter setting in the digital signal processing in the own station 4 based on the estimated transmission path characteristic of the optical transmission path (step S16). Note that Rx 3-1 and 3-2 may perform parameter setting in digital signal processing at the own station 4 based on the transmission path characteristic of the optical transmission path estimated by itself.

After the parameter setting, the optical node 4 transmits the signal light in the channel on which the initial process has been performed (step S17), and ends the control (step S18).
The processes in steps S10 to S18 may be performed in all of the optical nodes 4 that transmit the signal light of the control target channel, or the optical nodes 4 that transmit the signal light of the control target channel. May be implemented in at least one of the above.

As described above, in this example, before transmitting the training signal for estimating the transmission path characteristic of the optical transmission path, the training signal is expanded by expanding the passband of the training signal in the optical node 4. Loss to be reduced.
As a result, the transmission line characteristics of the optical transmission line can be estimated appropriately, and the parameters for digital signal processing can be set appropriately.

[2] First Modification By the way, the passband width of the training signal from the transmitter (Tx) to the receiver (Rx) varies depending on, for example, the number of optical nodes 4 through which the training signal passes.
Therefore, in this example, it is determined whether or not to perform control to expand the pass band of the channel through which the training signal is transmitted, according to the number of optical nodes through which the training signal passes. Further, when the control is performed, for example, some optical nodes 4 are configured so that the loss received by the training signal is equal to or less than a predetermined threshold, in other words, the training signal after transmission satisfies a predetermined reception quality. The control for expanding the passband of the channel is performed at.

The control method of this example will be described with reference to FIG.
As illustrated in FIG. 8, first, when control is started when a signal rises in a certain channel, the optical node 4-1 that is a transmission source of the training signal transmits information indicating control start and passage Information “1” regarding the number of nodes is notified to the optical node 4-2 (step S20).

When receiving the notification from the optical node 4-1, the optical node 4-2 notifies the next optical node 4-3 of the information indicating the start of control and the information “2” regarding the number of passing nodes (step S21). ).
Similarly, the optical nodes 4-3 to 4- (n-1) provide information indicating control start and information "3" to "n" regarding the number of passing nodes to the next optical nodes 4-4 to 4-n. -1 ".

In this way, each optical node 4 increases (counts up) information on the number of passing nodes by 1 and notifies the next optical node 4 to the optical node 4-n that is the receiving destination of the training signal. On the other hand, the number of optical nodes through which the training signal passes can be notified.
The optical node 4-n acquires the number of optical nodes (the number of passing nodes) through which the training signal passes based on the information notified as described above, and whether or not the number of passing nodes is larger than the upper limit number of nodes. Is determined (step S22). The upper limit number of nodes represents, for example, an upper limit value of the number of pass nodes so that the loss received by the training signal is less than a predetermined threshold without performing passband expansion control on the startup channel. Note that the upper limit number of nodes may be determined based on the measurement result obtained by measuring the loss received by the training signal, the pass bandwidth from the transmitter to the receiver, or the like by actual measurement or simulation.

  When it is determined that the number of passing nodes is equal to or less than the upper limit number of nodes (No route in step S22), the optical node 4-n ends the control and notifies the end of control to each optical node 4 (step). S35). Each optical node 4 notified of the end of control starts transmission of the training signal without expanding the passband in the WSS 43 and performs an initial process.

On the other hand, when it is determined that the number of passing nodes is larger than the upper limit number of nodes (Yes route in step S22), the optical node 4-n determines that the loss received by the training signal is equal to or greater than a predetermined threshold, and expands the passband. The optical node (control target node) 4 to be controlled is determined (step S23).
For example, the control target node is selected from the optical nodes 4 that do not affect other channels on the network path due to passband expansion control and have no restrictions on device control. Specifically, for example, control target node determination processing as exemplified in FIG. 9 is performed.

  As illustrated in FIG. 9, first, when the process of determining the control target node is started (step S40), the optical node 4-n expands the passband based on the upper limit node number and the pass node number. The number of optical nodes 4 to be controlled (number of nodes requiring control) is calculated (step S41). Specifically, for example, the optical node 4-n calculates a value obtained by subtracting the upper limit number of nodes from the number of passing nodes as the number of nodes requiring control. Note that the number of nodes requiring control may be larger than the value obtained by subtracting the upper limit number of nodes from the number of passing nodes.

Next, the optical node 4-n initializes the number of optical nodes 4 (number of control target nodes) determined as the target of passband expansion control to “0” (step S42).
Then, the optical node 4-n performs a process of determining whether or not each optical node 4 is the target of the control. First, whether there is an optical node 4 that has not been subjected to the determination process. Is determined (step S43).

If the determination process has been completed for all the optical nodes 4 (No route in step S43), the optical node 4-n ends the control target node determination process (step S53).
On the other hand, if there is an optical node 4 that has not been determined (Yes route in step S43), the optical node 4-n may have, for example, one optical node 4 among the optical nodes 4-1 to 4-n. By analyzing the channel monitoring information and the like, the usage status of both adjacent channels of the channel (control target channel) through which the training signal is transmitted is confirmed (step S44).

Here, when the WSS 43 has the configuration illustrated in FIGS. 3 and 5, as illustrated in FIG. 10, both adjacent channels (for example, λ1 and λ3) of the control target channel (for example, λ2) are in a passing state. Even if it is (ON), there exists a wavelength region (valley) where the intensity of the training signal decreases.
On the other hand, when the WSS 43 is a type having LCOS as illustrated in FIG. 6, both adjacent channels (for example, λ1 and λ3) of the control target channel (for example, λ2) pass as illustrated in FIG. In the state (on), there is no wavelength region (valley) in which the intensity of the training signal decreases.

For this reason, if the WSS 43 is an LCOS type wavelength selective switch and both adjacent channels of the control target channel are in the pass state, it can be considered that the pass band of the control target channel has already been expanded.
Therefore, the optical node 4-n determines whether or not the WSS 43 is an LCOS type wavelength selective switch and both adjacent channels of the control target channel are in a passing state (step S45). When the WSS 43 is an LCOS type wavelength selective switch and both adjacent channels of the control target channel are in a passing state (Yes route in step S45), the optical node 4-n sets the number of control required nodes to 1. Decrease (step S51). If the WSS 43 is not an LCOS type wavelength selective switch, the optical node 4-n may omit the processes in steps S45 and S51.

  Then, the optical node 4-n determines whether the number of control target nodes is equal to or greater than the number of control required nodes (step S50), and if the number of control target nodes is equal to or greater than the number of control required nodes (step S50). Yes route), the control target node determination process is terminated (step S53). If the number of nodes to be controlled is less than the number of nodes requiring control (No route in step S50), the optical node 4-n returns the process to step S43.

  On the other hand, even if the WSS 43 is not an LCOS type wavelength selective switch or the WSS 43 is an LCOS type wavelength selective switch, if either of the adjacent channels of the control target channel is not in a passing state (No route in step S45), the optical The node 4-n determines whether or not signal light is added or dropped in either of the adjacent channels of the control target channel (step S46). Specifically, for example, the optical node 4-n collects setting information related to the wavelength selective switch 43 of each optical node 4, and based on the collected setting information, signals are transmitted in either of the adjacent channels of the control target channel. It can be determined whether an add or drop of light is being performed. Note that the setting information regarding the wavelength selective switch 43 includes, for example, information regarding input / output destinations for each channel in the wavelength selective switch 43. That is, each optical node 4 has a function of transmitting the setting information in the own station 4 to the adjacent optical node 4 and sets the setting information received from the optical node 4 adjacent to the own station 4 in the setting in the own station 4. It may have a function of adding information and transmitting it to the next optical node 4.

  For example, as shown in FIG. 12, the WSS 43 includes an input port 47 to which signal light is input from the optical coupler 41, an add port 49 to which signal light is added, and an output port 48 that outputs signal light to the optical transmission line. For example, FIG. 13 illustrates a configuration in which the ch1 signal light is added, the ch2 and ch5 signal lights are passed, and the ch3 and ch4 signal lights are dropped. Input / output settings are made.

  At this time, when ch1 is a channel adjacent to the control target channel, if it is set to the pass state by the expansion control of the pass band of the control target channel, the signal light of ch1 included in the wavelength multiplexed signal light cannot be blocked, It becomes impossible to add the signal light of ch1 from the optical node 4. For this reason, it is desirable not to perform passband expansion control on the control target channel in the optical node 4 in which the added ch1 is an adjacent channel of the control target channel.

  In addition, when either ch3 or ch4 is an adjacent channel of the control target channel, the ch3 and ch4 signal lights included in the wavelength multiplexed signal light are set in the pass state by the expansion control of the passband of the control target channel. Is transmitted to the next optical node 4. For this reason, in the optical node 4 in which any one of the ch3 and ch4 to be dropped is an adjacent channel of the control target channel, it is desirable not to perform the passband expansion control on the control target channel.

Therefore, when the signal light is added or dropped in any of the adjacent channels of the control target channel (Yes route in step S46), the optical node 4-n controls the optical node 4 to expand the passband. Is determined as a non-control target that is not implemented (step S52).
Then, the optical node 4-n determines whether the number of control target nodes is equal to or greater than the number of control required nodes (step S50), and if the number of control target nodes is equal to or greater than the number of control required nodes (step S50). Yes route), the control target node determination process is terminated (step S53). If the number of nodes to be controlled is less than the number of nodes requiring control (No route in step S50), the optical node 4-n returns the process to step S43.

  On the other hand, when the signal light is not added or dropped in any of the adjacent channels of the control target channel (No route in step S46), the optical node 4-n passes through either of the adjacent channels of the control target channel. When the state is controlled, it is determined whether or not leakage light such as spontaneous emission (ASE) light circulates on the ring network (step S47). Specifically, for example, the optical node 4-n collects setting information related to the wavelength selective switch 43 of each optical node 4, and based on the collected setting information, signals are transmitted in either of the adjacent channels of the control target channel. It can be determined whether an add or drop of light is being performed. Note that the setting information related to the wavelength selective switch 43 includes, for example, information viewed at the input / output destination for each channel in the wavelength selective switch 43. That is, each optical node 4 has a function of transmitting the setting information in the own station 4 to the adjacent optical node 4 and sets the setting information received from the optical node 4 adjacent to the own station 4 in the setting in the own station 4. It may have a function of adding information and transmitting it to the next optical node 4.

  For example, as illustrated in FIG. 14, the optical transmission system 1 includes a ring network in which optical nodes 4-1 to 4-10 are connected in a ring shape. For example, among continuous ch1 to ch5, The signal light of ch4 (see the dotted arrow in FIG. 14) is added from the optical node 4-10, passes through the optical nodes 4-1 to 4-5, is dropped at the optical node 4-6, and ch2 Is added from the optical node 4-5, passes through the optical nodes 4-6 to 4-10, 4-1, and is dropped at the optical node 4-2. Consider the case.

  In such a case, as illustrated in FIG. 15, as a result of performing expansion control of the pass band of ch4 to transmit the training signal in ch4, ch3 and ch5 that are both adjacent channels of ch4 are in a pass state (in FIG. 15, As a result of the expansion control of the pass band of ch2 to transmit the training signal in ch2, the ch2 and ch5 rows in the column of the optical nodes 4-1 to 4-5) When both adjacent channels ch1 and ch3 are in the passing state (see the shaded portion of the rows of ch1 and ch3 in the columns of optical nodes 4-6 to 4-10 and 4-1 in FIG. 15), the optical node 4-1 to 4-10 pass ch3, and the ASE light in the ch3 band circulates on the ring network and oscillates to transmit to other channels. It can degrade the ability.

Therefore, in such a case (Yes route of step S47), the optical node 4-n determines the optical node 4 as a non-control target for which the passband expansion control is not performed (step S52). If the optical transmission system 1 does not have a ring network, the optical node 4-n may omit the process of step S47.
Then, the optical node 4-n determines whether the number of control target nodes is equal to or greater than the number of control required nodes (step S50), and if the number of control target nodes is equal to or greater than the number of control required nodes (step S50). Yes route), the control target node determination process is terminated (step S53). If the number of nodes to be controlled is less than the number of nodes requiring control (No route in step S50), the optical node 4-n returns the process to step S43.

  On the other hand, when it is determined that the optical transmission system 1 does not have a ring network, or the training signal does not circulate around the ring network (that is, the circulation of the training signal on the ring network can be avoided) (No route in step S47). The optical node 4-n determines that the optical node 4 is a target for passband expansion control (step S48), and increases the number of control target nodes by one (step S49). Note that the above “circulation” means that the training signal goes around the ring network at least once.

  Then, the optical node 4-n determines whether the number of control target nodes is equal to or greater than the number of control required nodes (step S50), and if the number of control target nodes is equal to or greater than the number of control required nodes (step S50). Yes route), the control target node determination process is terminated (step S53). If the number of nodes to be controlled is less than the number of nodes requiring control (No route in step S50), the optical node 4-n returns the process to step S43.

Information on the control target node determined as described above is superimposed on the supervisory control signal by the optical node 4-n, and is sequentially notified to the optical nodes 4- (n-1) to 4-2 via the OSC or the like. (Step S24 in FIG. 8).
As an example, the optical node 4-2 notified of the information on the control target node determines whether or not the own station 4-2 is the control target node based on the information (step S25). -2 is determined to be a control target node (Yes route in step S25), control for expanding the passband of the WSS 43 is performed (step S26), and information on the control target node is sent to the next optical node 4-1. Transfer (step S27). In the optical node 4-2, when the WSS 43 is a type having LCOS, the pass band of the control target channel may be expanded by controlling both adjacent channels of the control target channel to the pass state. Good.

On the other hand, when it is determined that the own station 4-2 is not the control target node (No route in step S25), the next optical node 4-1 is not related to the control target node without performing control for expanding the pass band of the WSS 43. Information is transferred (step S27).
Similarly, the optical node 4-1 notified of the information on the control target node from the optical node 4-2 determines whether or not the own station 4-1 is the control target node based on the information (Step S1). S28) When it is determined that the own station 4-1 is a control target node (Yes route in step S28), control is performed to expand the pass band of the WSS 43 (step S29). Also in the optical node 4-1, as in the optical node 4-2, when the WSS 43 is a type having LCOS, the control target channel is controlled by controlling both adjacent channels of the control target channel to the passing state. The passband may be expanded.

On the other hand, when it is determined that the own station 4-1 is not a control target node (No route in step S28), the control for expanding the pass band of the WSS 43 is skipped.
When the above passband expansion control is completed, the optical node 4-1 as the optical transmitter transmits a known training signal via the optical transmission line, and the optical node 4-n as the optical receiver The training signal transmitted from the node 4-1 is received, and the transmission path characteristics of the optical transmission path such as polarization mode dispersion and chromatic dispersion are estimated based on the reception result.

  Next, the optical node 4-n determines whether or not the above estimation process is completed (step S30). If it is determined that the estimation process is completed (Yes route in step S30), Rx (optical receiver) ) Digital signal processing initial parameters are set (step S30-1). The optical node 4-n notifies the completion of the estimation process and the estimation result to the optical nodes 4- (n-1) to 4-2 (step S31). Note that the information regarding the completion of the estimation process and the estimation result may be superimposed on the monitoring control signal and notified via the OSC or the like, for example. If it is determined that the estimation process has not been completed (No route of step S30), the optical node 4-n repeats the process of step S30 until the estimation process is completed.

As an example, if the optical node 4-2 notified of the information regarding the completion of the estimation process and the estimation result has expanded the pass band of the WSS 43, the optical node 4-2 restores the pass band (step S32), and the next optical node Information about the completion of the estimation process and the estimation result is transferred to 4-1 (step S33).
Similarly, when the optical node 4-1 is notified of completion of the estimation process and information related to the estimation result from the optical node 4-2, if the pass band of the WSS 43 is expanded, the optical node 4-1 returns the pass band to the original state and is notified. Based on the estimated result, initial parameters for digital processing of Tx (optical transmitter) are set (step S34). Note that returning the pass band of the WSS 43 to the original means changing the pass band of the WSS 43 to a pass band for signal light. In other words, when the bandwidth of the training signal is larger than the bandwidth of the signal light, it means that the pass band of the WSS 43 that has been expanded for the training signal is narrowed to the pass band for the signal light.

Here, a specific example of the control method is shown in FIGS. 16 (A) to 16 (D).
As illustrated in FIG. 16A, the optical transmission system 1 includes ten optical nodes 4-1 to 4-10. As illustrated in FIG. In the case where the WSS 43 has a pass band of 40 GHz (Gaussian Order 3) as the −3 dB bandwidth, for example, the pass bandwidth required at the initial process of the startup channel is 30 GHz as the −3 dB bandwidth .

However, as shown in FIG. 16B, when the training signal is transmitted with the pass bandwidth of the WSS 43 in each optical node 4 as it is, the pass bandwidth of the training signal in Rx3 after transmission is −3 dB band The width is 25 GHz, and the required passband width of 30 GHz cannot be satisfied.
Therefore, in this example, as illustrated in FIG. 16C, any five optical nodes (for example, the optical nodes 4-3 to 4-6, 4-, among the optical nodes 4-1 to 4-10). 9) in the WSS 43, the pass band width of the training signal in Rx3 after transmission is set by, for example, setting the passage of both adjacent channels of the control target channel transmitting the training signal, thereby expanding the pass band of the control target channel. Can be increased to 30 GHz, which is the required pass bandwidth.

After the initial process is completed by transmitting the training signal, as illustrated in FIG. 16D, based on the passband expanded in the WSS 43 in the optical nodes 4-3 to 4-6 and 4-9. By returning, channel utilization efficiency during signal light transmission may be improved.
[3] Second Modification In the above-described embodiment and the first modification, each optical node 4 implements the above-described control using OSC light. For example, the NMS uses GMPLS (Generalized Multi-Protocol Label Switching). The above control may be realized by using a TL1 (Transaction Language 1) command or the like.

FIG. 17 is a diagram illustrating an example of the configuration of the optical transmission system according to the present example.
An optical transmission system 1 ′ illustrated in FIG. 17 exemplarily includes an optical node 4-1 having an optical transmitter (Tx) 2 and an optical node 4-2 that relays signal light from the optical node 4-1. ˜4- (n−1), an optical node 4-n having an optical receiver (Rx) 3, and a network management device (NMS) 5 for managing each optical node 4. For convenience of explanation, Tx2 in the optical node 4-1 and Rx3 in the optical node 4-n are also written outside in FIG.

For example, as illustrated in FIG. 18, the NMS 5 includes a receiving unit 51 that receives various types of information from each optical node 4, a processing unit 52 that performs the above control based on the various types of received information, and a result of the control. A transmission unit 53 that transmits control information based on the optical node 4 is provided.
That is, the NMS 5 functions as an example of a control device of the optical transmission system 1 ′.
In addition, the processing unit 52 functions as an example of a control unit that performs control to expand a pass band for a known training signal in at least one optical node 4 through which the optical transmission path passes before transmitting the known training signal. .

Further, the processing unit 52 is an example of a processing unit that estimates the transmission path characteristics of the optical transmission path based on the transmission result of a known training signal transmitted in the optical transmission path after performing control to expand the passband. Function.
In the example shown in FIG. 17, the signal light transmitted from Tx2 is inserted (added) into the wavelength multiplexed signal light transmitted through the optical transmission line by the optical node 4-1, and then the optical nodes 4-2 to 4- ( n-1) is passed (through), branched (dropped) at the optical node 4-n, and received by Rx3. Note that the network configuration of the optical transmission system 1 ′ illustrated in FIG. 17 is merely an example, and the optical transmission system 1 ′ includes various types such as a ring type, a mesh type, a star type, a full connection type, a bus type, and a tree type. It may have the network form. Further, the optical transmission system 1 ′ may have a combination of each network form.

In the optical transmission system 1 ′ shown in FIG. 17, for example, FIG. 19 shows an example of a processing flow when the above-described control is performed using GMPLS.
In this case, as illustrated in FIG. 19, first, each optical node 4 acquires connection information with the optical node 4 adjacent to its own station 4 for each channel using GMPLS, and the acquired connection information is obtained. It manages (step S60). Note that this connection information may include, for example, setting information for each channel in the WSS 43 of each optical node 4.

Then, the NMS 5 inquires the connection information for each channel to each optical node 4 (step S61), and each optical node 4 notifies the connection information for each channel to the NMS 5 (step S62). .
Next, the NMS 5 creates communication path information for each channel based on the connection information for each channel notified from each optical node 4 (step S63). The communication path information may include, for example, information indicating in which optical node 4 the signal light of each channel is added, in which optical node 4 is passed, and in which optical node 4 is dropped. .

Further, the NMS 5 transmits to each optical node 4 an instruction regarding the setting related to the WSS 43 of each optical node 4 based on the communication path of the channel (start-up channel) to be newly opened (step S64).
Each optical node 4 performs input / output setting (intra-node path setting) of the startup channel in the WSS 43 in the local station 4 based on the instruction notified from the NMS 5 (step S65).

Next, in the startup channel, the NMS 5 measures (acquires) the loss received by the training signal, the pass bandwidth from the transmitter to the receiver, and the like by actual measurement or simulation (step S66).
Then, the NMS 5 determines whether or not the acquired pass bandwidth is larger than the required bandwidth (step S67). The required bandwidth refers to, for example, the pass bandwidth required for the training signal transmitted in the startup channel. The required bandwidth may be determined based on, for example, a penalty tolerance for a training signal transmitted in the startup channel.

When it is determined that the acquired pass bandwidth is larger than the required bandwidth (Yes route in step S67), the NMS 5 ends the control and notifies each optical node 4 of the end of control (step S74). Each optical node 4 notified of the end of control starts transmission of the training signal without expanding the passband in the WSS 43 and performs an initial process.
On the other hand, when it is determined that the acquired pass bandwidth is equal to or less than the required bandwidth (No route in step S67), the NMS 5 uses the same method as the control target node determination process illustrated in FIG. Determine (step S68).

Then, the NMS 5 notifies the determined control target node of the control start (step S69), and the control target node 4 notified of the control start has a pass band in the startup channel of the WSS 43 in its own station 4. The width is increased (step S70), a training signal is transmitted, and an initial process is performed.
The NMS 5 determines whether or not the initial process has been completed by receiving a completion report of the initial process from the optical node 4 that performs the initial process (step S71). If the initial process has not been completed (No in step S71). Route), the process of step S71 is repeated.

  On the other hand, if it is determined that the initial process has been completed (Yes route of step S71), the NMS 5 notifies the control target node 4 of the end of control (step S72), and the control target node notified of the end of control 4 returns the pass bandwidth in the startup channel to the original WSS 43 in the local station 4 (step S73), and starts transmission of signal light in the startup channel.

FIG. 20 shows an example of a processing flow when the above-described control is performed using, for example, a TL1 command in the optical transmission system 1 ′ shown in FIG.
In this case, as illustrated in FIG. 20, first, the NMS 5 inquires of each optical node 4 about setting information related to the WSS 43 in the own station 4 by using the TL1 command (step S80). The setting information is notified to the NMS 5 as the execution result of the TL1 command (step S81).

Next, the NMS 5 creates communication path information for each channel based on the setting information notified from each optical node 4 (step S82). The communication path information may include, for example, information indicating in which optical node 4 the signal light of each channel is added, in which optical node 4 is passed, and in which optical node 4 is dropped. .
Further, the NMS 5 transmits to each optical node 4 an instruction related to the setting related to the WSS 43 of each optical node 4 based on the communication path of the channel (startup channel) to be newly opened (step S83).

Each optical node 4 performs input / output setting (intra-node path setting) of the startup channel in the WSS 43 in the local station 4 based on the instruction notified from the NMS 5 (step S84).
Next, in the startup channel, the NMS 5 measures (acquires) the loss received by the training signal, the pass bandwidth from the transmitter to the receiver, and the like by actual measurement or simulation (step S85).

  Then, the NMS 5 determines whether or not the acquired pass bandwidth is larger than the required bandwidth (step S86). The required bandwidth refers to, for example, the pass bandwidth required for the training signal transmitted in the startup channel. The required bandwidth may be determined based on, for example, a penalty tolerance for a training signal transmitted in the startup channel.

When it is determined that the acquired pass bandwidth is larger than the required bandwidth (Yes route in step S86), the NMS 5 ends the control and notifies each optical node 4 of the end of control (step S93). Each optical node 4 notified of the end of control starts transmission of the training signal without expanding the passband in the WSS 43 and performs an initial process.
On the other hand, when it is determined that the acquired pass bandwidth is equal to or less than the required bandwidth (No route in step S86), the NMS 5 uses the same method as the control target node determination process illustrated in FIG. Determine (step S87).

The NMS 5 notifies the determined control target node of the control start (step S88), and the control target node 4 notified of the control start has a pass band in the startup channel of the WSS 43 in the own station 4. The width is increased (step S89), a training signal is transmitted, and an initial process is performed.
The NMS 5 determines whether or not the initial process is completed by receiving the completion report of the initial process from the optical node 4 that performs the initial process (step S90), and if the initial process is not completed (No in step S90). Route), the process of step S90 is repeated.

  On the other hand, if it is determined that the initial process is completed (Yes route in step S90), the NMS 5 notifies the control target node 4 of the end of control (step S91), and the control target node notified of the control end 4 returns the pass bandwidth in the startup channel to the original WSS 43 in the local station 4 (step S92), and starts transmission of signal light in the startup channel.

As described above, also in this example, before transmitting the training signal for estimating the transmission path characteristic of the optical transmission path, the optical node 4 expands the pass band of the training signal to perform training. Loss experienced by the signal can be reduced.
As a result, it is possible to appropriately estimate the optical fiber characteristics and appropriately set parameters for digital signal processing.

[4] Others The configurations and functions of the optical transmission systems 1 and 1 ′, the optical node 4, and the NMS 5 in the above-described embodiments and modifications may be selected or combined as appropriate. May be used. In other words, the above-described configurations and functions may be selected or used in appropriate combination so that the functions of the present invention can be exhibited.

  Further, for example, in the above-described first modification, the optical node 4 that is added or dropped on any of the adjacent channels adjacent to the channel on which the training signal is transmitted is determined as a non-control target. If neither of the adjacent channels is to be subjected to add or drop, the optical node 4 may be determined as a control target. In this case, the pass band for the training signal can be expanded to adjacent channels that are not subject to the add or drop. That is, the passband control unit 46 or the NMS 5 may have a function of determining a direction in which the passband of the control target channel is expanded according to the state of the adjacent channel.

The following supplementary notes are further disclosed with respect to the above embodiment and each modification.
[5] Appendix (Appendix 1)
A plurality of optical transmission apparatuses, based on a result of transmitting a known symbol sequence in an optical transmission path from one optical transmission apparatus through at least one optical transmission apparatus to another optical transmission apparatus; An optical transmission system control method for estimating the transmission path characteristics of
In the at least one optical transmission device through which the optical transmission path passes, control is performed to expand a pass band for the known symbol sequence,
Transmitting the known symbol sequence in the optical transmission line;
Estimating transmission line characteristics of the optical transmission line based on the transmission result;
A method for controlling an optical transmission system.

(Appendix 2)
After completion of the estimation, control is performed to restore the passband that has been subjected to the expansion control, and based on the estimation result, the one optical transmission device, the optical transmission device through which the optical transmission path passes, and the Making settings for digital signal processing in at least one of the other optical transmission devices;
The method of controlling an optical transmission system according to appendix 1, wherein:

(Appendix 3)
Control is performed to expand the passband of the at least one optical transmission device through which the optical transmission path passes so that the known symbol sequence after transmission satisfies a predetermined reception quality in the other optical transmission device.
The method of controlling an optical transmission system according to appendix 1 or 2, characterized by the above.

(Appendix 4)
Determining the number of optical transmission devices to be controlled based on the number of optical transmission devices that the optical transmission path passes,
The method of controlling an optical transmission system according to any one of appendices 1 to 3, wherein:
(Appendix 5)
Of the optical transmission devices that pass through the optical transmission path, an optical transmission device that is not used in an adjacent channel adjacent to a channel through which the known symbol sequence is transmitted is determined as a control target for expanding the passband. ,
The method of controlling an optical transmission system according to any one of appendices 1 to 4, wherein

(Appendix 6)
Among the optical transmission devices that pass through the optical transmission path, an optical transmission device in which signal light is inserted or branched in an adjacent channel adjacent to a channel through which the known symbol sequence is transmitted is controlled to expand the passband. Non-target,
The method of controlling an optical transmission system according to any one of appendices 1 to 5, characterized in that:

(Appendix 7)
When the optical transmission system includes a ring network,
Determining an optical transmission device to be controlled to expand the passband so that leakage light generated by performing control to expand the passband does not circulate around the ring network;
The method of controlling an optical transmission system according to any one of appendices 1 to 6, characterized in that:

(Appendix 8)
The optical transmission device through which the optical transmission path passes has a wavelength selective switch,
In the wavelength selective switch, control is performed to expand the passband by expanding a passband of a channel through which the known symbol sequence is transmitted to a passband of an adjacent channel adjacent to the channel.
The method for controlling an optical transmission system according to any one of appendices 1 to 7, characterized in that:

(Appendix 9)
The optical transmission device through which the optical transmission path passes has an LCOS (Liquid Crystal On Silicon) type wavelength selective switch,
In the LCOS type wavelength selective switch, the adjacent channel adjacent to the channel through which the known symbol sequence is transmitted is set in a passing state, thereby performing control to expand the passband.
The method for controlling an optical transmission system according to any one of appendices 1 to 7, characterized in that:

(Appendix 10)
A plurality of optical transmission apparatuses, based on a result of transmitting a known symbol sequence in an optical transmission path from one optical transmission apparatus through at least one optical transmission apparatus to another optical transmission apparatus; An optical transmission device through which the optical transmission line of the optical transmission system for estimating the transmission line characteristic of
A control unit that performs control to expand a passband for the known symbol sequence before transmitting the known symbol sequence;
A transmission processing unit that transmits the known symbol sequence through the optical transmission line after the control unit performs control to expand the passband;
An optical transmission device characterized by that.

(Appendix 11)
Based on the result of transmitting a known symbol sequence in a plurality of optical transmission apparatuses and an optical transmission path from one optical transmission apparatus through at least one optical transmission apparatus to another optical transmission apparatus, the optical transmission line A control device for estimating transmission path characteristics, and the control device of an optical transmission system comprising:
A control unit that performs control to expand a pass band for the known symbol sequence in the at least one optical transmission device through which the optical transmission path passes before transmitting the known symbol sequence;
A processing unit for estimating transmission path characteristics of the optical transmission line based on a transmission result of the known symbol sequence transmitted in the optical transmission line after the control unit performs control to expand the passband; With
A control device.

(Appendix 12)
A plurality of optical transmission apparatuses, based on a result of transmitting a known symbol sequence in an optical transmission path from one optical transmission apparatus through at least one optical transmission apparatus to another optical transmission apparatus; An optical transmission system for estimating the transmission path characteristics of
The at least one optical transmission device is the optical transmission device according to attachment 10.
An optical transmission system characterized by that.

(Appendix 13)
A plurality of optical transmission apparatuses, based on a result of transmitting a known symbol sequence in an optical transmission path from one optical transmission apparatus through at least one optical transmission apparatus to another optical transmission apparatus; An optical transmission system for estimating the transmission path characteristics of
Having the control device according to appendix 11,
An optical transmission system characterized by that.

1,1 'Optical transmission system 2,2-1,2-2 Optical transmitter (Tx)
3,3-1,3-2 Optical receiver (Rx)
4,4-1 to 4-10,4- (n-1), 4-n optical node 5 network management device (NMS)
41-1 to 41-4 Optical couplers 42-1 to 42-4 Optical amplifiers 43, 43-1, 43-2 Wavelength selection switches 44-1, 44-2 OSC processing devices 45-1, 45-2 46 Passband Control Unit 47 Input Port 48 Output Port 49 Add Port 51 Receiving Unit 52 Processing Unit 53 Transmitting Unit 431, 434 Optical Coupler 432-1 to 432-5 Passband Variable Filter 433-1 to 433-5 2 × 1 Optical Switch

Claims (10)

A plurality of optical transmission apparatuses, based on a result of transmitting a known symbol sequence in an optical transmission path from one optical transmission apparatus through at least one optical transmission apparatus to another optical transmission apparatus; An optical transmission system control method for estimating the transmission path characteristics of
In the at least one optical transmission device through which the optical transmission path passes, control is performed to expand a pass band for the known symbol sequence,
Transmitting the known symbol sequence in the optical transmission line;
Estimating transmission line characteristics of the optical transmission line based on the transmission result;
A method for controlling an optical transmission system. After completion of the estimation, control is performed to restore the passband that has been subjected to the expansion control, and based on the estimation result, the one optical transmission device, the optical transmission device through which the optical transmission path passes, and the Making settings for digital signal processing in at least one of the other optical transmission devices;
The method of controlling an optical transmission system according to claim 1, wherein: Control is performed to expand the passband of the at least one optical transmission device through which the optical transmission path passes so that the known symbol sequence after transmission satisfies a predetermined reception quality in the other optical transmission device.
The method of controlling an optical transmission system according to claim 1, wherein the method is a control method. Of the optical transmission devices that pass through the optical transmission path, an optical transmission device that is not used in an adjacent channel adjacent to a channel through which the known symbol sequence is transmitted is determined as a control target for expanding the passband. ,
The method of controlling an optical transmission system according to any one of claims 1 to 3, wherein: Among the optical transmission devices that pass through the optical transmission path, an optical transmission device in which signal light is inserted or branched in an adjacent channel adjacent to a channel through which the known symbol sequence is transmitted is controlled to expand the passband. Non-target,
The method of controlling an optical transmission system according to any one of claims 1 to 4, wherein When the optical transmission system includes a ring network,
Determining an optical transmission device to be controlled to expand the passband so that leakage light generated by performing control to expand the passband does not circulate around the ring network;
The method for controlling an optical transmission system according to any one of claims 1 to 5, wherein A plurality of optical transmission apparatuses, based on a result of transmitting a known symbol sequence in an optical transmission path from one optical transmission apparatus through at least one optical transmission apparatus to another optical transmission apparatus; An optical transmission device through which the optical transmission line of the optical transmission system for estimating the transmission line characteristic of
A control unit that performs control to expand a passband for the known symbol sequence before transmitting the known symbol sequence;
A transmission processing unit that transmits the known symbol sequence through the optical transmission line after the control unit performs control to expand the passband;
An optical transmission device characterized by that. Based on the result of transmitting a known symbol sequence in a plurality of optical transmission apparatuses and an optical transmission path from one optical transmission apparatus through at least one optical transmission apparatus to another optical transmission apparatus, the optical transmission line A control device for estimating transmission path characteristics, and the control device of an optical transmission system comprising:
A control unit that performs control to expand a pass band for the known symbol sequence in the at least one optical transmission device through which the optical transmission path passes before transmitting the known symbol sequence;
A processing unit for estimating transmission path characteristics of the optical transmission line based on a transmission result of the known symbol sequence transmitted in the optical transmission line after the control unit performs control to expand the passband; With
A control device. A plurality of optical transmission apparatuses, based on a result of transmitting a known symbol sequence in an optical transmission path from one optical transmission apparatus through at least one optical transmission apparatus to another optical transmission apparatus; An optical transmission system for estimating the transmission path characteristics of
The at least one optical transmission device is the optical transmission device according to claim 7.
An optical transmission system characterized by that. A plurality of optical transmission apparatuses, based on a result of transmitting a known symbol sequence in an optical transmission path from one optical transmission apparatus through at least one optical transmission apparatus to another optical transmission apparatus; An optical transmission system for estimating the transmission path characteristics of
A control device according to claim 8 is provided.
An optical transmission system characterized by that.

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